import java.util.Scanner;

public class Answer1 {
    //平方数

    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);

        long n=in.nextLong();

        long a=(long) Math.sqrt(n);
        long b=a*a;
        long c=(a+1)*(a+1);

        if(b-n > c-n) System.out.println(a+1);
        else System.out.println(a);
    }
}
